JP3204292B2 - Piezoelectric vibrator unit for inkjet recording head and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure generating chamber in which one surface of a pressure generating chamber is formed by a vibrating plate, a vertical vibrating piezoelectric vibrator is attached to the vibrating plate, and the piezoelectric vibrator is contracted and expanded. The present invention relates to a laminated piezoelectric vibration plate suitable for an ink jet recording head that generates ink droplets by expanding and contracting a generation chamber, a method for manufacturing the same, and a method for manufacturing a piezoelectric vibrator unit.

[0002]

2. Description of the Related Art Piezoelectric vibrators are used as drive elements in various fields because they are small and light in weight and can respond at high speed as compared with other mechanical actuators.
For example, when a piezoelectric vibrator in a longitudinal vibration mode as shown in Japanese Patent Application Laid-Open No. 4-366643 or US Pat. No. 5,453,770 is used for driving an ink jet recording head, a piezoelectric vibrator, a diaphragm and Contact area can be extremely small,
A resolution of 180 DPI or more can be realized.

In an ink jet recording head using a longitudinal vibration mode, as shown in FIG. 8, a piezoelectric vibrator B, B, B # is provided with a narrow gap behind a flow path unit A having a plurality of nozzles. The arranged vibrator unit C is inserted from the vibrator unit insertion opening E of the holder D, and the ink from the ink flow path is guided to the pressure chamber formed by the nozzle plate and the vibration plate. The piezoelectric vibrators B, B, B # driven according to the recording signal are configured to be pressurized and fly as ink droplets from nozzles.

[0004] The piezoelectric vibrator B in the longitudinal vibration mode uses a driving circuit as low as possible to simplify the driving circuit.
As shown in, the piezoelectric vibration material F and the electrode materials G and H are
The piezoelectric vibrating plate K is formed by laminating a plurality of piezoelectric vibrating plates K such that the electrodes do not overlap at one end and the thickness of the piezoelectric vibrating material F between the electrode materials G and H is extremely thin as 15 to 30 μm. (FIG. 9A) Thereafter, a DC voltage of about 70 volts is applied between the electrodes G and H to perform polarization processing (FIG. 9A).
(B)), this is divided into N having a size suitable for forming one piezoelectric vibrator unit,
(C)) is an intermediate.

Then, as shown in FIG. 10A, external electrodes P and Q connected to the electrodes G and H are formed at the front end and the rear end, respectively. The inactive area M is attached to the support plate R, and cut from a tip on the active area side by a dicing saw or a wire saw at a predetermined width, for example, at a pitch of 0.14 mm in the case of a 1/180 inch pitch. B, B, and B, and the unit is finished into a piezoelectric vibrator (FIG. 10).
(B)).

[0006] The piezoelectric diaphragm thus constructed is
Since one half is formed as a polarized region and the other half is formed as a non-polarized region, the dipole moment, which was at random by the polarization process, is aligned in the direction of the polarization axis and slightly shrinks. Is in the original state, the contracted portion and the non-contracted portion are present in the same material, and a warp occurs due to a so-called bimetal effect, and a line connecting the ends as shown in FIG. A gap ΔS is generated between the gap and the center.

[0007]

However, when the number of piezoelectric vibrators in the vibrator unit is about 30, the length of the piezoelectric vibrating plate is as small as about 5 to 6 mm. The gap amount becomes negligibly small, but when used as a piezoelectric vibrating plate constituting a piezoelectric vibrator unit of a recording head having, for example, 128 or more nozzle openings in one row in order to support high-density, high-speed printing. , A gap ΔS of 5 to 10 μm generated by polarization remains as it is as a gap between the piezoelectric vibrator and the island portion Q of the diaphragm P constituting the partition of the pressure generating chamber.

As shown in FIG. 11, these piezoelectric vibrators Re and Rc form a layer of an adhesive T at their ends and are joined to the island portion Q. However, the piezoelectric vibrators Re and Re at the ends are formed. ‥
And the island portion Q can be bonded via a layer of the adhesive T, but the central portion of the piezoelectric vibrator Rc, Rc # cannot be brought into contact with the vibration plate P because a large gap is generated.

Although it is conceivable to increase the thickness of the adhesive, it is impossible to transmit the displacement of the piezoelectric vibrator due to expansion and contraction of the pressure generating chamber because the adhesive layer acts as an elastic member. Becomes

It is also conceivable to flatten at least the surface in contact with the diaphragm by polishing or the like.
However, since the external electrode P needs to be formed again because of the polishing, it is necessary to form the external electrode again. However, since the electrode formation involves heating, the problem that the polarization that has been performed disappears, and furthermore, the time and effort for polishing are required. However, such a method cannot be adopted because it involves a serious problem such as damage or breakage.

The present invention has been made in view of such a problem, and an object of the present invention is to suppress the warpage of a piezoelectric vibrating plate caused by polarization processing as much as possible and eject ink droplets from a large number of nozzles. It is an object of the present invention to provide a vibrator unit which can be used. Another object of the present invention is to propose a method for manufacturing the above-described piezoelectric vibrator unit.

[0012]

According to the present invention, to solve such a problem, a first electrode layer serving as one pole and a second electrode layer serving as the other pole are made of a piezoelectric material. In a piezoelectric vibrator unit in which a plurality of piezoelectric vibrators, which are alternately stacked and interleaved at predetermined pitches, are fixed at their rear ends to a support plate, a polarization process is performed on a region facing the support plate. And an inactive region that does not generate a piezoelectric effect due to the drive signal.

[0013]

Since the polarization processing is performed on almost the entire piezoelectric vibrating plate, warpage due to partial polarization is prevented.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a first embodiment of the present invention. FIG. 1 shows an embodiment of a method for manufacturing a piezoelectric vibrating plate, and at least the size of a vibrator unit (for example, a length of 21 mm, a width of 5.times.
A paste of a piezoelectric material, for example, lead zirconate titanate (PZT) is applied to the substrate 1 to a predetermined thickness, for example, 15 microns using a mask so as to have a thickness of 5 mm and a thickness of 0.5 mm. A piezoelectric material layer 2 called a green sheet is formed (FIG. 1A).

Next, the tip 2a, which contacts the diaphragm of the ink jet recording head, and at least one side 2a
A conductive paste is applied to the surface of the piezoelectric material layer 2 by a thickness of 1 to 3 μm using a mask that shields only a certain width of b, and a first electrode layer 3 (FIG. 2A) serving as a drive electrode is laminated (FIG. 1).
(B)).

As shown in FIG. 2 (a), the first electrode layer 3 has a tip 3a between a side (tip side) of the piezoelectric material layer 2 which is in contact with the vibration plate of the pressure generating chamber, and at least. One end 3c of the side has regions 2a and 2b where the piezoelectric material layer 2 is exposed, and the rear end 3b is formed so as to be exposed from the piezoelectric material layer 2.

Using a mask, a paste of a piezoelectric material is applied using a mask so as to overlap the surface of the first electrode layer 3 and the first piezoelectric material layer 2 exposed from the electrode layer 3 as described above. The second piezoelectric material layer 4 is formed (FIG. 1C).

Next, the boundary between the active region and the inactive region is defined by a blank portion 4a in the vicinity of the boundary between the active layer and the inactive layer by using a mask that shields the conductive relationship by a certain width that can interrupt the conductive relationship. Divided second electrode layer 5 and dummy electrode layer 6
Is formed (FIG. 1 (d)).

As shown in FIG. 2B, the second electrode layer 5 extends at least until the tip 5a is exposed from the piezoelectric material layer 4, and the dummy electrode layer 6 has the tip 6a.
Is opposed to the rear end 5b of the second electrode layer 5 across the blank portion 4a, and the rear end 6b is embedded in the piezoelectric material layer 4, and at least one side 6c is located on the side of the piezoelectric material layer 4. It is formed so as to be exposed from one side.

Thereafter, the above steps (a) to (d) of laminating the piezoelectric material layer and the electrode layer are repeated by the required number of layers, and the layer is naturally dried to a predetermined degree of drying.
By firing at about 0 ° C., a piezoelectric vibrating plate 10 as shown in FIG. 3A is completed.

Although the rear end 3b of the first electrode layer 3 of the piezoelectric vibration plate 10 is exposed from the piezoelectric material layers 2 and 4, at least the side surfaces on which the dummy electrode layer 6 is exposed are formed on the piezoelectric materials 2 and 4. Is embedded. Further, the second electrode layer 5 is exposed from the tip, and the side surface 6c of the dummy electrode 6 is exposed to the outside.

Next, as shown in FIG. 3B, an external electrode 11 connected to the end 3b of the first electrode layer 3 exposed at the rear end of the piezoelectric material is exposed from the front end of the piezoelectric material. The external electrode layer 12 connected to the tip 5a of the second electrode layer 5 is formed, and the third external electrode 13 connected to the side 6c of the dummy electrode layer 6 exposed from the side is formed. These external electrodes 11, 12, and 13 can be formed by depositing a metal having a thickness of about 1 μm or applying a conductive paint.

Then, the second electrode layer 5 and the dummy electrode layer 6
And the external electrodes 12 and 13 connected to the
A voltage of about 75 volts that can polarize the piezoelectric material layers 2 and 4 is preferably applied to the external electrode 11 connected to the electrode layer 3 for about 1 minute in a heated state.

As a result, the active region where the first electrode layer 3 and the second electrode layer 6 face each other and the inactive region where the first electrode layer 3 and the dummy electrode layer 6 face each other are polarized together. You.

Since almost the entire area of the piezoelectric vibrating plate 10 is polarized as described above, a warped piezoelectric vibrating plate as shown in FIG. 3C is completed even after the polarization process. If necessary, the external electrode 13 formed for connection with the dummy electrode layer 6 may be removed by an operation such as polishing or cutting.

FIG. 5 shows a piezoelectric vibrating plate constructed as described above.
As shown in (a) and (b), the inactive region 7 is fixed to a support plate 15 made of a free-cutting material such as a piezoelectric material, ceramic, or glass, and the active region, that is, the first electrode layer is formed. A desired piezoelectric vibrator unit is completed by dividing a region corresponding to 3 and the second electrode layer 5 at a predetermined pitch by a dicing saw or a wire saw to separate the piezoelectric vibrator 16. Reference numeral 17 in the figure denotes a conductive member that connects the external electrodes 12 in parallel and also serves as reinforcement.

Although the piezoelectric vibrating plate is fixed to the support plate 15 in the above-described embodiment, it is directly fixed to the holder D (FIG. 8) for fixing the flow path unit A constituting the pressure generating chamber and the like. Obviously, the same effect is obtained even when the above-mentioned operation is performed.

In the above-described embodiment, the piezoelectric vibrating plate serving as one piezoelectric vibrator unit is formed one by one. However, as shown in FIGS. In this embodiment, a piezoelectric material layer having an area of four vibration plates is formed, and four patterns 20 of the first electrode layer are formed on the surface of the piezoelectric material layer at least at the tip end as shown in FIG. After forming the piezoelectric material layer at a constant pitch with an interval 21 corresponding to the width of the space, and forming a piezoelectric material layer on the surface thereof, as shown in FIG. The electrode layer 23 may be formed and fired, and the boundary of each pattern may be cut as a cutting line 24 by a dicing saw or the like. Further, it may be fired in the vertical direction in the figure as a size of a plurality of sheets, and may be divided as shown in FIG.

In the above embodiment, the rear end 3b of the first electrode layer 3 and the front end 5a of the second electrode layer 5
Further, the dummy electrode layer 6 is laminated so that the side end 6c is exposed from the piezoelectric material layer. However, as shown in FIG. 7, firing is performed in a state where the dummy electrode layer 6 is embedded in the piezoelectric material layer. Only the rear end 3b, the front end 5a, and the side end 6c can be exposed, and the cutting is performed along the lines 30, 31, 32, and 33 having a size suitable for forming a piezoelectric vibrator. Good.

Further, in the above-described embodiment, almost the entirety of the inactive region is polarized, but the inactive region has the minimum degree of warpage due to the degree of shrinkage due to the presence or absence of the polarization treatment. Obviously, only the region needs to be polarized.

[0031]

As described above, according to the present invention, the first electrode layer serving as one pole and the second electrode layer serving as the other pole are alternately laminated with a piezoelectric material interposed therebetween. In a piezoelectric vibrator unit having a rear end side fixed to a support plate, a plurality of piezoelectric vibrators divided at a predetermined pitch are subjected to polarization processing in a region facing the support plate, and a piezoelectric signal is generated by a drive signal. Since it is configured as an inactive region that does not produce an effect, almost all of the piezoelectric vibrating plate is subjected to polarization processing, and partial shrinkage due to polarization can be eliminated to prevent warpage.

[Brief description of the drawings]

FIGS. 1A to 1D are views showing one embodiment of a method for manufacturing a piezoelectric vibrating plate according to the present invention.

FIGS. 2A and 2B are diagrams showing patterns of a first electrode layer, a second electrode layer, and a dummy electrode layer, which are alternately formed with a piezoelectric material layer interposed therebetween. FIGS.

FIGS. 3A to 3C are views showing the piezoelectric vibrating plate in a state immediately after firing, a state in which an external electrode is formed, and a state in which a polarization process has been completed, respectively.

FIGS. 4A and 4B are diagrams illustrating one end face of a piezoelectric vibrating plate and an electrode layer at a central portion, respectively.

FIGS. 5 (a) and 5 (b) are a perspective view and a sectional view, respectively, showing an embodiment of the piezoelectric vibrator unit of the present invention.

FIGS. 6A and 6B show another embodiment of the method for manufacturing a piezoelectric vibrating plate according to the present invention, with a structure of a first electrode layer, a second electrode layer, and a dummy electrode layer. FIG.

FIG. 7 is a diagram showing another embodiment of the present invention.

FIG. 8 is a diagram showing an example of an ink jet recording head using a piezoelectric vibrator in a longitudinal vibration mode.

FIGS. 9A to 9C show states of a piezoelectric vibrating plate constituting a conventional piezoelectric vibrating unit immediately after firing,
It is a figure which shows the state after the polarization process, and the state cut | disconnected by the predetermined size.

FIGS. 10A and 10B are diagrams showing a conventional manufacturing process of forming a piezoelectric vibrator unit from a piezoelectric vibrating plate, respectively.

FIG. 11 is a diagram schematically showing a connection state between a piezoelectric vibrator and a diaphragm when a recording head having a large number of nozzles is formed by a conventional piezoelectric vibrator.

[Explanation of symbols]

 2, 4 piezoelectric material layer 3 first electrode layer 5 second electrode layer 6 dummy electrode layer

Claims (3)

(57) [Claims] A plurality of first electrode layers serving as one pole and a second electrode layer serving as the other pole are alternately laminated with a piezoelectric material interposed therebetween and are divided at a predetermined pitch. In a piezoelectric vibrator unit having a rear end side fixed to a support plate, the piezoelectric vibrator is configured as an inactive region in which a polarization process is performed on a region facing the support plate and a piezoelectric effect is not generated by a drive signal. Piezoelectric vibrator unit for inkjet recording head. 2. The piezoelectric vibrator unit for an ink jet recording head according to claim 1, wherein a dummy electrode layer electrically isolated on the same plane as said one electrode layer is formed in said inactive region. 3. A first electrode layer having a size such that a rear end side is exposed from the piezoelectric material layer, a front end side and at least one side are buried in the piezoelectric material layer, and a front end side is exposed from the piezoelectric material layer. A second electrode layer having a rear end located in the active region; a front end having a predetermined gap from the second electrode layer; a rear end being buried inside the piezoelectric material layer; Obtaining a fired product alternately provided with dummy electrodes exposed from the material layer; an external electrode layer connected to the first electrode layer at a rear end and at a front end of the second electrode layer; and the dummy electrode Forming an external electrode layer connected laterally to the layer; and applying a polarization voltage between the first electrode layer, the second electrode layer, and the dummy electrode layer via the external electrode to perform polarization. A step of performing a treatment, and forming the laminate after the polarization treatment on the dummy electrode. Fixing the piezoelectric vibrator to the support plate at the opposing area and dividing the piezoelectric vibrator into piezoelectric vibrators at a predetermined pitch.